The present invention is directed to a method and device for feeding printed products, for example from a stack using a feeding device such as a gripper drum.
U.S. Pat. No. 6,082,724 describes a variable speed sheet material assembly apparatus with a feed mechanism driven by a feed motor, and is hereby incorporated by reference herein. Sheet material articles are delivered from the feed mechanism to moving pockets of a pocket conveyor driven by a conveyor drive motor. The feed motor operating speed is varied as a function of the conveyor drive motor to coordinate the relative speeds of the feed motor and the conveyor drive motor for proper delivery of the sheet materials from the feed mechanism to the pockets of the pocket conveyor.
Feeding devices comprising rotating drums for hoppers typically run at a constant speed over the entire 360 degrees of rotation. The feed drum is operated at a rotational speed that is sufficiently slow to avoid tearing of the printed product or other malfunctions. For example, it has been known to run the feed drum at half the speed of the conveyor, as a safer operational speed for the feed drum is often more limited than a speed feasible for a conveyor. However, twice as many feed drums are then required to collect a product of a certain size, and the set up time can become a longer and more complex operation due to a speed mismatch between the rotating feed drum and the conveyor.